WASTE TO WEALTH—Utilization of iron oxide-slag derived from
electric arc furnace in the degradation of water pollutants
Norhaslinda Nasuha, a PhD student at School of ChemicalEngineering, Universiti Sains Malaysia and member of Reaction Engineering &Adsorption (READ) research group lead by Prof. Dr. Bassim H. Hameed, reports
new Fenton-like catalyst for the degradation of Reactive Black 5 dye. Their
results were recently published in the Journal of the Taiwan Institute ofChemical Engineers (Elsevier) with an Impact Factor of 2.848.
“Our aim in this work was to develop a low-cost, effective and
robust Fenton-like catalyst for the degradation of reactive dyes in aqueous
solution. In searching for possible waste material, iron rich slag derived from
an electric arc furnace (EAFS) from steel making industry was found to be a
good potential” explained Prof. Bassim.
Organic pollutants containing dye wastewater has become a serious
threat to public health and the hydrosphere. To comply with the limit set by
USEPA, advanced oxidation process (AOPs) has attracted enormous attention in
wastewater treatment due to its green, efficient, and simple method. However,
the economic expediency is still restricted with limitations, such as cost of
catalyst, post-treatment requirement, and loss of catalyst occurring during the
reaction process.
Byproducts of steel industries are known as metal-rich sources
depending on the type of steel being manufactured. Electric arc furnace (EAF)
plays an important role in making modern steel and dominates the overall steel
production in Malaysia. With respect to end-products, slag is formed from lime
to collect undesirable components in the EAF slag (EAFS), which is classified
as steel waste. In the long term, the slag not only occupies a great quantity
of land, but gives rise to environmental pollutions. Various recycling methods
have been reported to utilize this material including in road construction,
cement production, and ceramic tile making.
To date, characteristics of EAFS have revealed that it contains
more than 25% iron oxide and other complex metal oxides. In addition, it can be
easily recovered through magnetic separation. Therefore, the EAFS is a
potential heterogeneous catalyst in environmental application.
In particular, magnetite and maghemite contained in the EAFS will
work efficiently as a heterogeneous catalyst in AOPs, especially Fenton-like
reactions. The use of EAFS as Fenton heterogeneous catalyst will be beneficial
for producing a highly active radical (HO•) and allowing redox reaction without
structure change. However, thermal treatment is required to improve the
functionality of the EAFS.
“From an application in Fenton-like process, the activated EAFS
(A-EAFS) presents better performance in degradation of Reactive Black 5 than
raw EAFS”, said PhD student Nasuha.
According to Nasuha, A-EAFS exhibits high degradation of RB5 with
insignificant iron leaching even after 10 consecutive cycles of oxidative
degradation under optimal conditions.
Moreover, the team found that A-EAFS preserved its surface activity
by keeping its crystalline phase (i.e., iron oxide) and similar morphological
features even after 10 cycles of reaction. The interaction between maghemite
and magnetite is believed to play a dominant role in accelerating the redox
cycles of active sites in the generation of Fe2+, thereby allowing the
continuous oxidative degradation of RB5 in the heterogeneous Fenton-like
reaction.
The characteristic of EAFS has opened new ways for developing
another advanced material. “We are now exploring the full potential of EAFS as
material for reaction and separation applications with colleagues from READ
group”, Nasuha said.
